The present invention is directed toward a patch unit for use in fiber optic distribution systems and the like and more particularly to such a patch unit adapted for being particularly versatile and efficient.
Communication systems of the type contemplated for use with the patch unit of the present invention were initially established for transmission of various types of information including audio, video and digital data in the form of electrical signals through electrical transmission lines. Such information may of course include telephone signals, television signals, digital data, FM audio signals and the like. More recently, these electrical conductors have commonly been replaced by optical transmission systems where the information is transmitted through cables or the like formed from optical fibers.
The fiber optic cable may be in the form of one or more individual fibers or it may take the form of a bundle of many fibers. Here again, large numbers of fibers may be assembled in sets such as ribbons each including a flat array of, for example, 12 fibers. On the other hand, all or part of the fibers may be individually buffered, that is, contained within separate plastic tubes of relatively larger diameter to facilitate handling of the fibers and protect them from damage. In any event, fiber optical systems have become particularly desirable for such applications because of their bandwidth capabilities for handling greatly increased amounts of information, particularly in comparison with electrical transmission lines.
With the expanding use of such fiber optic systems, generally the same configurations of distribution networks have been employed for providing communications to given sets of users as in the earlier electrical communication systems. For example, service to large numbers of users in a given area, such as a city, university or other complex, has been established with central offices or hubbing locations for providing service to groups of users in generally localized areas. A hubbing location commonly replaces a central office in localized areas such as universities and the like. The hubbing location is then interconnected with a central office by a trunk line for associating it with other communication networks. Accordingly, the term "central office" is used broadly in connection with the present invention and includes hubbing locations and other alternative means.
In order to provide service for each user from the central office, it has been common practice to provided dedicated lines between the central office and each given user through local networks in the form of conventional star or bus configurations for example. With large numbers of users in a fixed location such as large buildings or portions of a university, large numbers of lines have been assembled in cables or the like to facilitate interconnection of all of the users with the central office.
At the same time, it has been necessary to provide for changes in the numbers and locations of such users within a given area. In the past, this was accomplished by shifting of dedicated lines from one user to another. Thus, where shifting patterns of users have occurred, it has often been necessary to reroute entire cables or portions of cables at very considerable expense.
A solution to this particular problem has been achieved in a manner disclosed in a co-pending patent application Ser. No. 644,206, entitled FIBER OPTIC DISTRIBUTION NETWORK, filed Aug. 24, 1984. the invention of that co-pending reference being assigned to the assignee of the present invention.
The above noted co-pending reference discloses a fiber optic distribution system for overcoming problems of the type outlined above. In particular, the co-pending reference discloses a method and apparatus for forming a fiber optic distribution system for providing communication access from a central office to a group of users generally in a localized area. For that purpose, the system of the co-pending reference contemplates a continuous optical fiber primary loop arranged to pass in the vicinity of each user in the group, the invention contemplating means arranged at spaced apart intervals along the primary loop for permitting selective interconnection of the users with the primary loop in order to place them in communication access with a central office. At the same time, fibers in the loop which are not employed for those users are interconnected in order to establish continuity throughout the loop. Thus, the additional fibers may be used for servicing users adjacent other points in the loop.
To make the fiber optic distribution system of the co-pending reference more effective and versatile, it is necessary to provide means at spaced apart locations about the primary loop for permitting users to be selectively interconnected with one or more fibers in the loop while continuity is established for the remaining fibers. It will be apparent that a device capable of satisfying this particular function within the fiber optic distribution system of the co-pending reference will also be useful in other fiber optic applications.